With war appearing imminent, the question arises: why did diplomacy fail? Efforts to accomplish Iraq's disarmament without war fell apart in sharp disagreements among council members over the time, methods, and the ultimate aims in Iraq.

In November, the U.N. Security Council agreed that Iraq must disarm. Council Resolution 1441, passed unanimously by the council, warned that Baghdad would face what it termed "serious consequences" if it did not do so.

Diplomacy collapsed into disagreement over just what "serious consequences" involved, and how and when they should be applied.

Speaking on behalf of the U.S.-led bloc in the Council, British Ambassador Jeremy Greenstock blamed the collapse on an unnamed nation's threatened use of a veto. The nation was later acknowledged to be France.

"We have had to conclude that Council consensus will not be possible in line with resolution 1441," he said. "One country in particular has underlined its intention to veto any ultimatum, 'no matter what the circumstances'. That country rejected our proposed compromise even before the Iraqi government, and has put forth suggestions that would roll back on the unanimous agreement of the Council in Resolution 1441."

Former U.S. Ambassador William Luers is president of the United Nations Association, a private group devoted to promoting the aims of the United Nations. He says there was never any argument over the need to disarm Iraq. But he says the U.S. message got watered down because the Bush administration espoused other aims in Iraq such as "regime change" that went beyond just disarmament.

"Some states, I think particularly France, saw that we probably had multiple reasons for wanting to do this, it was not simply to disarm Iraq, as stated in 1441. But they were getting reasons from other things that were being said in Washington that it was about regime change, that it was about democratizing the region. I think from a diplomatic point of view, the United States did diffuse a strong message that was agreed to on November 8 in the resolution 1441," Mr. Luers said.

He adds that the new Bush doctrine of pre-emptive action against perceived threats also made some council members uneasy.

Yale University professor Jean Krasno, who co-authored a recent book on the United Nations and Iraq, says debate was heated, and caused some deep wounds.

"So, I think that rather than to reach out to our allies and friends, we have driven wedges between our allies and friends," she said. "So it has not made it easier on the security council to discuss these issues."

Mr. Luers says the fact that the United States felt the need to go back to the security council is significant.

"And I think that places the security council still at the center of how nations think about the use of military force, that whether or not they go along with everything the security council says, they want to justify their actions somehow within terms of the U.N. Charter. And I think that is a strong norm, and I think it shows the continuing relevance of the security council," he said.

Will there be a backlash in the security council as the result of U.S. military action? Ms. Krasno says that depends on what happens on the battlefield in the coming days and weeks.

"If it is fairly quick, if it is fairly clean, if there are not a lot of civilian casualties involved, then on I think it is going to be harder for there to be a backlash. If it is a mess, and there are a lot of atrocities and casualties that take place and a humanitarian disaster which could happen, then I think the coalition or the partners are going to be more vulnerable to condemnation," she explained.

In any event, analysts say, the United Nations will again be needed for rebuilding Iraq after the guns fall silent.